1. Field of the Invention
This invention relates to a roller changer for a machine, such as a rotary press, the rollers of which must be changed.
2. Description of the Prior Art
A rubber roller has been used in an inking arrangement of a rotary press as a roller for distributing ink between an ink cylinder and the roller and for transferring the ink to a printing plate in order to supply an uniform ink film onto the surface of the printing plate.
Surface quality of the rubber roller undergoes degradation with time and the roller itself must be changed, whenever necessary.
Conventional roller changers are described, for example, in Japanese Utility Model Laid-Open No. 15145/1986 and Japanese Utility Model Laid-Open No. 108025/1990.
In the first reference, i.e., Japanese Utility Model Laid-Open No. 15145/1986, the tips of a pair of roller support arms continuously provided to the rotary shaft which is disposed between the frames of a printing unit are engaged with both shaft end portions of a printing roller supported between the frames, and then the printing roller is released from support. The support arms are driven for rotation by a motor provided to the printing unit, and the printing roller can be taken out between the adjacent printing units. The printing roller is put onto a truck which is kept on standby between the printing units and is changed.
In the latter reference, i.e., Japanese Utility Model Laid-Open No. 108025/1990, a roller changer equipped with a stocker for storing arms and rollers that are moved back and forth by a hydraulic cylinder is moved into an arc of the printing unit and is set to a predetermined position. The arms are moved forth and engaged with the printing roller and after the cap of the support device of the printing roller is opened, the arms are moved back along guide rails disposed in the printing unit so that the roller can be guided and moved and is then stored in the stocker.
Next, the arms are engaged with a replacing roller which is in advance stocked and are guided and moved along the guide rails to the roller support device. Furthermore, the cap of the support device is closed so as to support the roller, and in this way, the roller is changed.
However, the apparatuses of the prior art involve the following problems.
In the apparatus described in Japanese Utility Model Laid-Open No. 15145/1986, the replacing arms and the driving motor must be disposed for each roller which needs to be changed in the printing unit. Therefore, the apparatus requires extremely wasteful investment.
In appartus described in Japanese Utility Model Laid-Open No. 108025/1990, the guide rail must be disposed for each roller which needs to be changed, on the machine frame. Therefore, the space for the guide rail becomes necessary. Since the guide rail is disposed, members which must be fitted to the frame surface of the machine become very complicated, and this places a greater burden on an operator at the time of maintenance and inspection. Moreover, this apparatus is solely directed to the rollers disposed inside the arc of the printing press.
For the reasons described above, the development of a roller changer which is simple is structure, can cope with any change of a roller which requires changing, and can reduce the burden on the operator are desired.